The purpose of this project is to explore the potential of new materials as implants for internal fixation of long bone fractures. The purpose will be to determine whether a plate which permits stress transmission across the fracture will result in earlier achievement of normal bone strength after diaphyseal fracture than in the case of a very rigid stainless steel plate. Carbon materials can be manufactured with a modulus of elasticity similar to bone (2 x 10 to the 5th power kg/cm2) and at the same time can be manufactured with sufficient strength characteristics to permit its use as a compression plate for internal fixation. The strength characteristics of carbon plate immobilized fractures will be studied in vitro. Experimental fractures in dog radii will be treated by internal fixation with conventional stainless steel compression plates on one side and compared with similar fractures treated with carbon plates and Titanium-6 Aluminum-4 Vanadium (Ti-6Al-4V) alloys on the other side. At various stages in the fracture healing process, the animals will be sacrificed and the strength of the fracture site will be tested. Methods which will be used in this study include bioengineering testing procedures for determination of lateral binding strength and torsional strength. Cyclic loading tests will also be performed. Histologic techniques will be used to evaluate the rate of remodeling. For this purpose, the rate of redevelopment of new Haversian systems will be studied with the help of tetracycline labeling techniques. An effort will be made to correlate the strength of the fracture with its histology, in particular with the rate of redevelopment of Haversian systems. BIBLIOGRAPHIC REFERENCES: Simon, B.R., Woo, S. L-Y., Olmstead, S.R., and Akeson, W.H.: Parametric Stress Analysis of Internal Fixation Plating. Abstract published in Proceedings of the 22nd Orthopaedic Research Society, Vol. 1, 2, 1976. Coutts, R.D., Akeson, W.H., Woo, S. L-Y., Gonsalves, M., and Amiel, D.: Comparison of Stainless Steel and Composite Plates in Healing of Diaphyseal Osteotomies - Report on a Short Term Study. Orthopedic Clinic of North America, Vol. 7, No. 1, 223-229, 1976.